The invention relates to a height-adjustable support for semi-trailers or the like or a supporting device of a vehicle, in particular of a semi-trailer or of a trailer.
Such supports are arranged in pairs at the front of semi-trailers and can be brought telescopically into the support or transport positions. Such supports are known from EP 0 675 029 and EP 1 104 369 B2, for example. Said supports have drive mechanisms, which can be driven by means of hand cranks and which have a fast gear to be extended into the support position or to be retracted into the transport position, and a low gear, by means of which the front area of the semi-trailer can be lifted or lowered. In addition to the drive mechanisms, the mechanical outlay is further increased by spindle drives, bearing parts etc., which causes substantial manufacturing costs and unfavorably a high support weight. In practice, it is particularly disadvantageous that even in the so-called fast gear approx. 20 crank rotations are necessary to extend or retract the support, which is the case for all other such supports on the market. In order to save this onerous physical labor and the time required therefor for the driver, it was tried to provide a motor drive. This led to the solution proposed in DE 102 41 905 A1. Here, a motor unit is attached to each pair of the supports, which means additional attachment and securing elements and further mechanical outlay and, thus, an increase in weight. Modern tractor trailers with air-sprung rear axle assemblies can also lift or lower the front area of a semi-trailer via the fifth wheel during hitching and unhitching. Winding up or lowering by means of the semi-trailer supports is therefore not necessary. Instead, in practice, only a very fast load-free extension and retraction of the supports from the transport position into the support position and vice versa is of utmost priority. In addition, a support as a utility vehicle component and product of large-scale production should be as light-weight as is possible and be inexpensive to manufacture.
The object underlying the invention is to provide a height-adjustable support or supporting device for semi-trailers, which can be brought into its support position and also back into the transport position very rapidly, i.e. with few crank rotations only or with an efficient power drive, wherein the support is light-weight, the manufacturing outlay is small and the manufacturing costs are low.